Effects of processing parameters on the micro-drilling through fast hole electroerosion and laser trepanning in Inconel 718

Electroerosion and laser drillings are techniques used in manufacturing microholes in materials that are difficult to machine. Small diameter holes (between 0.18 and 2 mm) are commonly used in the aeronautical industry and gas turbine components as elements of the cooling system of hot side blades. This study aims to evaluate the effect of different machining parameters on the dimensional and microstructural quality of microholes obtained by the two manufacturing techniques cited. These effects were yield and dimensional analysis, the presence of micro-cracks, and width of the zone affected in the micro-drilling of Inconel 718. For this, microholes were produced through fast hole drilling electroerosion, using two electrode materials, copper and brass, and through Nd:YAG laser micro-drilling by trepanation. A central composite statistical design was defined to evaluate the influence of input parameter variations. Results were compared and showed that although the laser trepan process productivity is higher than that of electroerosion, laser drilling generates a greater concentration of cracks in the HAZ (heat-affected zone) when compared to the microholes manufactured by electroerosion. Therefore, assessment of the process to be used depends on the features one wants to optimize. Each manufacturing process has advantages and limitations that must be taken into consideration for selecting one of the techniques, and the project of the component should present the essential requirements for choosing the proper manufacturing process.